Vacuum-blast pickups for sheet material



May 8, 1962 c. H. KRETZ, JR 3,033,562

VACUUM-BLAST PICKUPS FOR SHEET MATERIAL 2 Sheets-Sheet 1 Filed Feb. 5, 1960 INVENTOR. CHARLES H. KRETZ, JR.

A T TORNEY May 8, 1962 c. H. KRETZ, JR

VACUUM-BLAST PICKUPS FOR SHEET MATERIAL 2 Sheets-Sheet 2 Filed Feb. 5, 1960 INVENTOR. CHARLES H. KRETZ; JR BY A 7'TORNEV VACUUM-BLAST PICKUPS FoR SHEET MATERIAL Charles H. Kretz, Jr., 313 Rolling Hills Drive,

San Mateo, (Ialif.

Filed Feb. 5, 1960, Ser. No. 7,068

7 Claims. (Cl. 271-46) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by and for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to pickups for sheet material and more particularly to pickups using a combination of vacuum and blast. The invention also relates to a method handling sheet material in stacks. The apparatus of the invention is especially useful in collating machines of the type shown in my pending filed December 5, 1956, and is an improvement on the pickup assembly described in that patent application, reference to which may be made for the background setting of this invention. The collating machine of the aforementioned patent application is a machine in which stacks of sheet material, such as paper, to be collated move as a station while pickup means, a sheet unit relative to a collector moving with the unitary motion, gradually pick up from each stack and deposit it at the collector station asthat stack passes adjacent the collector station.

Priorart pickups of the type shown in the aforementioned application for the handling of sheet material in stacks comprise. a movable assembly including vacuum cups, suckers, or the like adapted to engage the top sheet of material in a stack adjacent its leading edge and a blast such as an air blast directed against the leading edge of the top sheet in the stack and other adjacent sheets so as to separate the upper sheet from those next to it. With such pickup assemblies having essentially no elements other than those just described, the top sheet of a stack is picked upnear its leading edge, but its trailing edge is allowed the droop downward. When such a sheet with its drooping trailing edge is moved relative to a collector into which collector the sheet is to be deposited, thedrooping portion of the sheet may strike an edge of the collector which sometimes causes the sheet to be knocked off the pickups and lost to the collating operation. Also, such prior art pickups sometimes pick up two sheets together, which is undesirable. An object of the present invention is to provide a method for handling sheet material in stacks which will certainly separate the top sheet from. the stack and will bend it and grasp it in such a manner.

that it is crimped and thus the sheet remains relatively rigid, rather than having its trailing edge drooping, so

that it can be readily deposited in a collector or otherwise.

disposed of without danger of being knocked off or falling off the pickup assembly.

Another object of the invention is to provide pickup. apparatus of a type suitable to carry out the method of.

the invention.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a front elevation partially in cross section of a preferred embodiment of the apparatus of the invention, with the paper-retaining lip omitted for clarity;

FIG. 2 is a top view of the embodiment of FIG. 1;

FIG. 3 is an elevation view taken along the line 33in FIG. 2;

FIG. 4 is an elevation view partially in cross section, taken along the line 4-4 in FIG. 2; and

application, Serial No. 626,553,-

FIG. 5 is a cross section elevation view taken along the line 5+5 of FIG. 2. Y

I The Method of the Invention I at'two substantially spaced points defining a line, lying in the surface of the material when the sheet is plane, relatively close to one boundary of the sheet and the sheet is held at these points in such amanner that the straight line lying in the surface of the material and passingthrough, Y

the two points remains as a straight line oriented generally horizontally, the sheet will droop because of its weight and hang down from the line of support. Ordinary paper such as used inwriting, printing, and mimeographing falls into .this category of flexible sheet material as may also plastics, fiber products, metal foil, and materials of other compositions.

The method of the invention is top sheet from a stack of sheet material and holding it in such a c onfi guration that it doesnotdroop, and retaining it in this configuration until it is.released, for example,.

intoa collector. The methodaccomplishesflthe' functions of separating at least a part of the topsheet from contact with the next sheet so that two sheets -are not removed together from the stack and of making the top sheet rigid so that the stack and it can be bodily separated from each other while it remains rigid and does not droop.

The method comprises bending the top sheet of a stack in such' a way that the sheet becomes rigid by'virtue of being bent or having a crimp put in it so that it will, so to speak, support its own weight through its stilfness without drooping when held at as few as two points substantially spaced apart. The method further comprises.

the removal, bodily, of the top sheet from the stack which can be accomplished either by leaving the stack in its original position and moving the top sheet away from it or by holding the top sheet still and removing the stack from it or by a combination of these two procedures wherein the top sheet and the stack are each moved in opposite directions away from their original positions.

The method of the invention is applicable to sheets of material of practically any shape: round, rectangular, irregular, etc. The sheets may be oriented in any of several directions: horizontally, vertically, orat an angle to the vertical. In carrying out the method of the invention, the top sheet of a stack is bent in such a manner as to render the sheet relatively rigid. The sheet is grasped at at least two spaced points to retain the sheet in the rigid configuration. The grasping of the sheet mayoccur prior to the bending or subsequent thereto. After being grasped and bent, the sheet is retained 'in its. rigid configuration while the sheet and the stack are separated from each,

otherf The sheet is held in this rigid position until it is released from the grasps.

By way of example only, several applications of the method are described herein with reference to a common sized sheet of paper considered to be 8 x 11 inches in size, designating the 11-inch edges as the sides and the 8-inch edges as the top and bottom.

One application of the method of the invention would be grasping the top sheet of a stack of such paper at two points located on a midline running from top to bottom of the sheet and, for convenience, relatively close to the top and bottom, say one inch from each such edge. j These two points, when the sheet is plane, define a straight line,

' each other in space, the two points moving away from the Patented May 8, 1962.

directed to removing the stack in the process so that the top sheet becomes convex towards the stack, then the sheet becomes stiff or rigid in the direction parallel to the sides so that when it is separated from the stack, either by moving the grasped points away from the stack or moving the stack away from the top sheet, or by a combination of such motions, the paper remains rigid without drooping, being perhaps inthe form of a catenarian cylinder or the like. In contrast, if the sheet were held at the same places, not in accordance with the invention, but in such a manner that the midline passing through the points was retained as a straight line, as it is when the sheet is plane, the two long sides would hang down with the sheet bending about the midline and taking a shape somewhat resembling the same general type cylinder but concave downward toward the stack.

If the sheet is now to be moved bodily in the direction ofv its short dimension (i.e., in the direction parallel to the top and the bottom) for the purpose of depositing it in thecollector, for example, then it can be seen that the sheet will move readily past any upstanding side of the collector when it is held according to the method of the invention in a rigid configuration whereas, if his held in drooping fashion, not according to the invention, the drooping portions of the sheet may very well brush against an upstanding side of the collector and produce undesirable results such'as folding the sheet as it enters the collector or causing a jam if sheets are deposited in rapid sequence in the collector or being knocked from the grasp at the two points of suspension and hencerbeing lost from the collection process.

Another application of the method of the invention envisions grasping the rectangular sheet at two substantially spaced points lying on a line which, when the sheet is plane, is generally parallel to say a long side of the sheet and is located relatively closer to one such long edge rather than lying in the middle of the paper Consider the rectangle formed by dropping normals to the long edge from these two points. A point lyingwithin this rectangle, and conveniently generally equidistant from the short sides of this rectangle and relatively close to the said long edge of the sheet is retained in contact with the next sheet, as by pressing the top sheet against the stack, and the top sheet is bent so that the two points to be grasped are moved away from the next sheet. The two points to be grasped are then grasped and with the third point still held in its aforedescribed position, the sheet assumes a rigidity by virtueof the crimps placed in it, there being a tendency to bend about an axis parallel to the top and bottom edges of the sheet for the reason that the said third point is located intermediate the short sides of the aforementioned rectangle and also a tendency to bend about an axis parallel to and relatively close to the said long edge of the sheet for the reason that the said third point is located intermediate the long sides of the aforementioned rectangle;

Although the method described made reference to the sheet material being rectangular in shape and the grasp points being on a line parallel and close to one edge, and made reference to the sheet material as being plane, none of these conditions is necessary for the accomplishment of the method of the invention so long as the general relative locations of the several points are maintained. Shapes of materials other than rectangles can be used. The grasp points need not lie on a line parallel to an edge of the material, but can be diagonal or more or less haphazardly located. The sheets of material need not necessarily be plane and, in fact, when stacks of paper are used in the method, they are often initially warped. The stack of material need not necessarily be horizontal and the paths of the top sheet and the stack in separating from one another need not be necessarily in the direction of the thickness of the stack of material. For example, the top sheet can be slid ofl? relative to the stack instead of being lifted off from the stack or any 4 s combination of such motions can be used with either the stackremaining stationary and the top sheet moving, orvice versa, or motion of both elements taking place.

In using the method of the invention, although various quence of steps can be varied. For performing the function of bending the paper, various items of equipment can be used. For example, an air blast directed against the edges of the sheets in a stack close to the top of a stack can be used to assist in separating the top sheet from contact with the next sheet and to assist in bending the top sheet. Also, suction devices at properly spaced points can bend the sheet While a restraining element holds in its original position a point intermediate the areas subjected to the greatest displacement in the bending process. Friction grasping devices such as rubber fingers, rubber rollers and the like can also be used to accomplish the bending and the gripping functions. Additional bends can be produced about points other than the one aforementioned point of restraint to assist in separating the top sheet from contact with the next sheet and in generating a rigid configuration. Conveniently such other bends can be made to occur about points as fulcrums located intermediate the'aforementioned point of restraint and each of the grasp points. One preferred embodiment of an apparatus well suited to carry out the method of the invention is the following: 7

Apparatus of The Invention By way of a simplified explanation of the construction and operation of the illustrated preferred embodiment, the invention may be considered for the moment as 'being applied to a collating machine of the type described in my aforementioned pending patent application. That machine comprises an assembly of supports for sheet materialmounted to move as a unit relative to a base so that each sheet material support in turn passes adjacent a collector station. The assembly of supports for sheet material may move as a unit relative to the base in any of numerous ways such as, for example, having the supports mounted in the manner of a Ferris Wheel, or mounted like a train traveling on a closed loop of track, mounted on an endless belt, mounted for reciprocation on tracks or other guides, or mounted for rotation about an axis through the base. The machine further comprises pickup means for picking up a sheet of material from each support, which pickup means is mounted to move with the assembly of supports relative to the base and also to undergo additional motion toward and away from a stack of paper in its respective support so that as the assembly of supports moves relative to the base, the pickup means gJadually picks up a sheet of paper from its support and deposits it at the collector station as it passes adjacent the collector station. For illustration purposes, the embodiment of the invention shown in the drawing may be regarded as applied to an assembly of supports mounted for rotary motion relative to a base. These supports, of which one is indicated generally by the numeral 1, are generally located circumjacent the axis of rotation and can be held in position in any convenient manner such as being mounted on separate arms like the spokes of a wheel, but preferably they .are located on a rotatable disc 2 mounted for rotation about an axis passing transversely to the plane of a disc and through a base not shown. The axis can be thought of as lying in a plane perpendicular to the plane of a paper and off to the left beyond the boundaries of FIG. 1. The support ,viewed in FIG. 1.

The pickup assembly comprises a pair of vacuum pickups or suckers or the like generally indicated at 10, conveniently provided in identical blocks 12 and 14 and adapted to engage the top sheet 16 of a stack16' of sheet material in a support 1 near the leading edge of the sheet. Each of the blocks also is provided with a step or shoulder 17 toencourage bending of the top 7 sheet of material to facilitate its separation from the next sheet.

Each vacuum pickup is shown as including .a suction cup 18 inserted in a counterbore in its respective block. The vacuum is supplied through a bore 20 in the block to which it is transmitted from a pipe 22 connected by a flexible tube or the like 24 to a vacuum pump or mania fold. The vacuum supply pipe 22 as well as a compressed air supply pipe 26 serves as support for blocks 12 and 14 which-are held to them, by set screws 28 or thalike. j' V The. compressed air pipe 26, supplied through tube 30 with air from a pump or manifold not shown, transmits compressed air through abore 32 in each of blocks 12 and 14 to a blast opening or nozzle 34. Although, as is evident in FIG. 5, the port 34 for the air blast is shown as located entirely some distance below the horizontal surface of the block 40 forming the step 17, it is sometimesfdesirable to increase the size of the port so that the openingextends upward in FIG. until it is fiush with said surface. This arrangement is particularly useful when sheet material having a strong tendency to pronounced curling at the edges is used. In such a case, the horizontal surface forming the step 17 serves as a footto limit'the curling of the paper andthe blast nozzle 34 is, then in a position to blowair between the top sheets instead of completely under them. I

The pickup assembly 36, preferably adjustably mounted as by threads and locknut 38 in block 40 carried by pipes 22 and 26 to which it is fixed by set screws 42. i

The pickup assembly is shown as supported by drive rod 44 to which the rest of the pickup assembly is fastened by virtue of block 46 which is fixed to pipes 22 and 26 by set screws 48 and to which is fixed drive rod 44 by set screw 59. Drive rod 44 is mounted for reciprocation, by cam or other means not shown, in bearing 52 of disc 2.

Operation V The operation of the illustrated embodiment is as follows: The drive rod 44 descends through'bearing 52 in FIG. 1 until the pin 36 rests on top of the stack of material in the stack support 1 as shown in FIG. 1 preferably generally close to one edge thereof. Air under pressure is thereafter admitted to pipe 26 while a vacuum is applied to pipe 22. The air blast directed through port 34 blows against theedges of the sheet material in the stack which tends to separate the upper sheet from contact with the next sheet. Assisting the separation operation are the suckers and the steps or ledges '17. The:

suckers 10 attract and grasp the top sheet 16, thus bending the sheet initially about the bottom of pin 36 as a fulcrum and also subsequently, in general, about the shoulders or steps 17. The shoulders 17 limit the motion of the portions of the sheet 16 which engage the shoulders 17 to a distance away from the top ofthe stack which is less than the distance of the suckers 10 from the top of the stack. This causes an additional bending or further includes an abutment pin.

, 6 crimping of the sheet 16 and allows an air passage in the region of the block 12 lying between the shoulder 17 and the sucker 10, which controls the vacuum in the sucker 10 as an additional safeguard against picking up two sheets. It also further discourages the second sheet from adhering to thefirst' sheet since the second sheet would be compelled to bend on a different radius. The bending of the paper occasioned by restraining its forward region with pin 36 and raising portions of it to engage the suckers 10 causes the sheet 16 to assume arigid con- 7 figuration displacing the main portion of the sheet away from the stack of material as shown in FIGS. 1, 3 and 4. The drive rod 44 then rises through the bearing 52 raising the pickup assembly so that the assembly carrying with it the top sheet 16 is bodily separated from the stack of material. However, before the pickup assembly starts to rise, the air blast is preferably cut ofi to'preclude any tendency of the second sheet to float up with the first sheet. Rotation of the disc 2 carries the sheet 16 over a collector into which the sheet 16 is dropped by releasing the vacuum applied to the suckers 10, the sheet having been retained in its rigid configuration until released from the suckers.

It will be apparent from the foregoing that inv the operation of the apparatus, the abutment or stop pin 36 comes to rest against the top sheet of material in the stack at a point relatively close'to the leading edge of the sheet and. located intermediate the substantially spaced suckers asmeasured in the direction of the said leading edge. The suckers are seen to be located along a line parallel to the leading edge of the sheet and placed further away from this edge than the pin 36', the suckers being located in a plane displaced outward from the top sheet of the stack measured in the direction of the thickness of the stack. The shoulders 17 lie intermediate the tip of the pin 36 and their respective suckers. That is, they are further back from the-leading edge thanis the pin 36 but i not as far back as the suckers and they are displaced from the top of the stack not quite as far as the suckers 10. For simplicity, the stack has been illustrated as showing the sheets of material all lying fiat or plane and with the tips of the suckers 10 lying in the same plane and their center lines lying on a line parallel to the front edge of the sheet. Similarly, the shoulders 17 have been shown as lying in a plane parallel to the planes of the sheets and on a line parallel to the leading edges of the 7 sheets. The pin 36 has been shown as lying midway between planes passing through the center line of the suckers, respectively, and perpendicular to the leading edge of the top sheet. However, none of these specific arrangements is necessary for the successful operation of the invention. The suckers need not lie in exactly the same plane nor need they be located at the same distance back from the leading edge of the. stack. The pin need not be exactly centrally located relative to the suckers and the shoulders 17 need not be symmetrically located. As long as the pin 36 is generally close to the leading edge and is at least as close to the leading edge of the sheet as is the line joining the suckers and is located generally intermediate the planes passing, respectively, through the suckers perpendicular to the leading edge of the sheet, then the pin 36 will perform its function. Similarly, the shoulders 17 may be located within a range of positions so long as they remain generally intermediate the tip of the pin and the tips of the suckers as regards distance back from the leading edge of the stack and distance away from the top sheet of the stack.

As previously pointed out, the member 2 is regarded leading edge has been used for convenience only as a means of identifying a convenient reference line, and is significant when the motion of the element 2 is assumed a to be out of the paper towards the observer in FIG. 1.

As previously indicated, the configuration of the sheet material in the stack need not be rectangular nor plane. The contour of the sheets may be any desired shape and the position in the stack may be in the form of curved surfaces, as often happens with the warping tendencies of some paper,.rather than a plurality of planes.

Although for simplicity and convenience in description, reference has been made to the points of contact of pin 36, shoulders 17, and suckers with the sheet material, it is to be understood that the contacts can be, and usually are, over a measurable region rather than merely at a geometrical point. The shape of the areas of contact is relatively unimportant. For example, in some embodiments of the invention, small pins and adjustable screws have been used to provide the limiting abutments in place of shoulders 17.

The position of the tip of'the pin 36 is varied by screw ingit in or out of the block ill to adjust it to the ideal position for whatever sheet material is being used. If the sheet material is relatively heavy and/or stifier than ordinary paper, the tip of the pin must not be so far away from the level of the suckers since the suckers would perhaps be unable to attract and grasp this type of material from too great a distance. If the apparatus is to be used with material which is not truly flexible within the meaning of that term, as previously set forth, then the tip of the pin 35, the abutments 1'7, and the suckers 10 may all be adjusted to the same level since. in this case separation of the top sheet of material from the stack and drooping do not appear as problems. An example of such a case would be sheet material constituted by the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is 1. The method of handling, in a stack, sheet material of a character subject to drooping which comprises retaining at its original location inthe original configuration of the stack a point on the top sheet located relatively close to one edge thereof; bending said top sheet about said point so as largely to separate said top sheet from contact with the next sheet and to crimp said top sheet into a relatively rigid configuration; grasping said sheet at two substantially-separated points thereof located at least as far from said edge as said first point and on either side of a plane containing said first point and normal to said edge; while said sheet is grasped and held 7 in the rigid configuration so produced, bodily separating said sheet and said stack from each other; said top sheet being maintained free of contact with any object pressing it at said two separated points against said next sheet in said stack during the interval of time spanned bythe aforedescribed steps of said method; and'retaining said sheet in said rigid configuration until released from said grasps.

2..An' apparatus of the character described comprising a support for a stack of sheet material, a vacuum pickup assembly for picking up a single sheet of material from the top of. said stack, said vacuum pickup assembly comprising a framework mounted for-motion relative to the stack support and including an" abutment adapted to engage the top surface of the stack of 'sheet material in said stack support and thus stop the motion of said pickup assembly relative to said stack and retain, while it remains so engaged, the portion of the top sheet of material in the stack at substantially its original location; said abutment being locatedso as to be adapted to engage said top sheet relatively close to one edge thereof; a pair of sucker tips substantially spaced from each other, one on each side of said abutment and pasteboard. To adjust 'all three categories of abutment to the same level, the pin 36 is screwed into the block 40 until it is level with the shoulders 17 and sucker tips 18' are replaced by slightly longer tips which project out from their counterbores to the level of shoulders 17.

Other types of restraints than pin 36 and the like can be used for fulcrums for bending. For example, a jet or blast of air directed normal to the top sheet would serve as well. Various gripping devices other than suckers can also be used for grasping the sheet'material. Rubber fingers, rollers and the like have been previously mentioned for this purpose.

Although the term sucker or sucker tip is used in this specification and generally may be thought to imply a rubber tip such as illustrated for example in U.S. Patent No. 2,163,274, it is intended to include a mere hole in a block such as block 12, a rubber washer or the like in a counterbore, a suction pipe such as shown in US. Patent No. 326,124 or any similar element.

Although the pickup assembly is shown as preferably generally close to one edge of the stack of sheet material, its position can be varied, if desired. If it were placed so that the suckers spanned the midline of the top sheet, then the pin 36 would be relocated in line with the suckers and shoulders 17 could be eliminated or relocated in line with the suckers intermediate the pin 36 and the suckers, and the blast nozzles would preferably be relocated to direct the blast against the edges of the stack generally normal to the leading edge.

Obviously many other modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within spaced at least as. far back from the said edge of the top sheet of material as is said abutment and so mounted on said framework as to remain out of contact With said top sheet of material while said top sheet is flush against the second sheet in said stack, whereby to prevent said sucker tips from pressing said top sheet against said second sheet in said stack; said elements being so arranged that when said vacuum is applied to'said sucker tips, said top sheet is bent largely out of contact with the i next sheet into a relatively rigid configuration so that it can be carried away from said stack without drooping. 3. The apparatus of claim 2 further including means for directing an air blast against the edges of said sheet material in said stack to assist separating the top sheet from contact with the second sheet and to bend the said top sheet into position so that it can readily be grasped by said sucker tips.

4. The apparatus of claim 3 further including a pair of abutrnents each located respectively intermediate said first abutment and one of said sucker tips as regards distance from said edge and distance from said stack support.

5. The apparatus of claim 2 further including means for adjusting with reference to said framework the relative distances of said first abutment on theone hand and said suckers on the other hand from said stack support.

6. An apparatus of the character described for handling in a stack sheet material of a character subject to droop-. ing comprising means for retaining a point on the top sheet relatively close to one edge thereof in the location in contact with the next sheet that it finds itself in the original configuration of the stack; means for bending the top sheet of said stack away from said point so that said sheet is largely separated from-the next sheet and is rendered into a substantially rigid configuration; means for grasping said top sheet at two substantially spaced points located at least as far from said edge as said first point and on either side of a plane passing thrOugh said first point normal to said edge to retain said top sheet in said rigid configuration; means limiting the action of said grasping means relative to said top sheet to prevent said grasping means from pressing said top sheet against the second sheet in said stack; and means for bodily separating said top sheet and said stack from each other while said sheet is held in said rigid configuration and for retaining said sheet in said rigid configuration until it is released from said grasps.

7. The method of handling, in a stack, sheet material of a character subject to drooping which comprises retaining at its original location in the original configuration of the staok a point on the top sheet located relatively close to one edge thereof; bending said top sheet about said point so as largely to separate said top sheet from contact with the next sheet and to crimp said top sheet into a relatively rigid configuration; grasping said sheet at two substantially separated points thereof located at least as far from said edge as said first point and on 20 either side of a plane containing said first point and normal to said edge; producing additional bends in said top sheet, during said bending step, about two points each located respectively intermediate the said first point and each of the said second mentioned points respectively as regards distance back from said edge and the distance away from the top of said stack; while said sheet is grasped and held in the rigid configuration so produced, bodily separating said sheet and said stack from each other; said top sheet being maintained free of contact with any object pressing it at said two separated points against said next sheet in said stack during the interval of time spanned by the aforedescribed steps of said method; and

retaining said sheet in said rigid configuration until released from said grasps.

References Cited in the file of this patent UNITED STATES PATENTS 853,910 Tyden May 14, 1907 1,501,582 Cheshire July 15, 1924 1,911,884 Darbaker May 30, 1933 2,594,373 Watson Apr. 29, 1952 

